1) Field of the Invention
This invention relates generally to fabrication of a semiconductor device and more particularly to a structure and method for forming a capacitor on a semiconductor structure by depositing a yttrium barium copper oxide layer over a first plate electrode layer at room temperature using a sputtering process.
2) Description of the Prior Art
Currently, oxide/nitride/oxide (ONO) or oxide/nitride (ON) stacks are primarily used as capacitor dielectric layers in DRAM fabrication. However, as device dimensions continue to shrink, capacitors formed using ONO or ON as the capacitor dielectric material are not able to provide the necessary capacitance with the reduced surface area.
New high dielectric constant materials have been developed to provide increased capacitance for a given surface area. Among these newly developed materials are Ta2O5, BST, and PZT. Each of these materials suffer drawbacks for use as a capacitor dielectric material for mass production of silicon-based intergrated circuits.
For example, Ta.sub.2 O.sub.5, BST, and PZT all have high leakage currents. While these leakage currents can be reduced using a high temperature anneal, high temperature anneals are detrimental to DRAM devices. Also, BST and PZT are difficult to deposit as thin films.
The importance of overcoming the various deficiencies noted above is evidenced by the extensive technological development directed to the subject, as documented by the relevant patent and technical literature. The closest and apparently more relevant technical developments in the patent literature can be gleaned by considering the following patents.
U.S. Pat. No. 5,075,281 (Testardi) shows a yttrium barium copper oxide (YBa.sub.2 Cu.sub.3 O.sub.6) high dielectric constant layer for capacitors fabricated by heating a pre-formed sample of YBa.sub.2 Cu.sub.3 O.sub.6 material to a temperature of at least 850.degree. C. and rapidly quenching it.
U.S. Pat. No. 5,348,894 (Gnade et al.) discloses various high K dielectric layers.
U.S. Pat. No. 5,605,858 (Nishoka et al.) shows a yttrium oxide capacitor dielectric.
U.S. Pat. No. 5,821,598 (Butler et al.) discloses a yttrium barium copper oxide infrared detector.
U.S. Pat. No. 5,851,896 (Summerfelt et al.) shows various oxide layers for high dielectric materials.
U.S. Pat. No. 5,555,486 (Kingon et al.) shows a "YBCO" (yttrium barium copper oxide) as a conductive metal oxide for a capacitor rather than as a capacitor dielectric.